1. Field of the Invention
The invention relates to an organic dye and, more particularly, to an organic dye used in photoelectric conversion devices.
2. Description of the Related Art
The demand for energy conservation triggered the search for alternate renewable energy sources. Recently, Gratzel and O'Regan have proposed a new type of solar cell known as a dye-sensitized solar cell (DSSC), which they claimed to be more efficient than other commercially available solar cells. The proposal has drawn much interest from solar cell researchers in academia and industry. Typically a dye-sensitized solar cell is constituted with four parts including an anode/cathode for providing a channel for current flow, a metal oxide (generally TiO2) semiconductor for accepting and transporting electrons, a photosensitizer, and an electrolyte for transporting holes. The materials and the junctions of the four parts in the dye-sensitized solar cell play important roles for efficiency of the cell. Most particularly, the photosensitizer (or dye) is critical in determining the efficiency of the dye-sensitized solar cell. Accordingly, it is essential to identify a dye that can provide good efficiency for the dye-sensitized solar cell.
Currently, in order to yield devices high in conversion efficiency, a ruthenium based complex (such as N3 dye(cis-dithiocyanato-bis(4,4′-dicarboxy-2,2′-bipyridine) ruthenium)) is used as a sensitizing dye. However, costs of the dye itself are high, and further problems remain also in the supply thereof. Due to the high absorption coefficient, various structures, and accessibility of organic compounds, the Attempts wherein an organic dye for replacing is used as a sensitizing dye have already been made. It is well known that having high absorption coefficient is one of the most important parameters for being a good photosensitizer.
However, currently, no substitute organic dye has replaced the ruthenium based complex due to low conversion efficiency, and stability and durability issues of devices using the same. There is, therefore, still a need for an organic dye with high absorption coefficient and high conversion efficiency that may be employed in photoelectric conversion devices.